Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES:
Net income	$ 315,434	$ 327,454
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	35,232	30,438
Provision for depreciation and amortization	30,729	28,824
Amortization of investment security premiums, net	20,436	18,758
Investment securities (gains) losses, net	(3,874)	(6,641)
Net gains on sales of loans held for sale	(7,881)	(4,770)
Origination of loans held for sale	(187,792)	(149,397)
Proceeds from sales and repayments of held for sale	194,344	156,637
Net (increase) decrease in trading securities	(428)	(4,886)
Stock-based compensation	10,365	9,555
(Increase) decrease in interest receivable	229	(5,021)
Increase (decrease) in interest payable	5,938	689
Increase (decrease) in income taxes payable	23,530	30,107
Other changes, net	(58,928)	14,964
Net cash provided by (used in) operating activities	377,334	446,711
INVESTING ACTIVITIES:
Proceeds from sales of investment securities (A)	379,641	193,047
Proceeds from maturities/pay downs of investment securities (A)	1,007,553	1,222,998
Purchases of investment securities	(1,306,607)	(1,520,235)
Net (increase) decrease in loans	(357,438)	(3,588)
Long-term securities purchased under agreements to resell	(150,000)	(100,000)
Repayments of long-term securities purchased under agreements to resell	0	100,000
Purchases of land, buildings and equipment	(29,441)	(21,358)
Sales of land, buildings and equipment	2,029	2,342
Net cash provided by (used in) investing activities	(454,263)	(126,794)
FINANCING ACTIVITIES:
Net decrease in non-interest bearing, savings, interest checking and money market deposits	(230,229)	(177,368)
Net increase (decrease) in certificates of deposit	411,098	(94,906)
Net increase (decrease) in federal funds purchased and securities sold under agreements to repurchase	(315,115)	354,979
Repayment of long-term borrowings	(163)	(224)
Net increase in short-term borrowings	248,734	0
Purchases of treasury stock	(119,970)	(39,575)
Accelerated share repurchase agreement	(150,000)	0
Issuance of stock under equity compensation plans	(3)	(10)
Cash dividends paid on common stock	(85,533)	(75,261)
Cash dividends paid on preferred stock	(6,750)	(6,750)
Net cash provided by (used in) financing activities	(247,931)	(39,115)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease)	(324,860)	280,802
Cash, cash equivalents and restricted cash at beginning of year	1,209,240	524,352
Cash, cash equivalents and restricted cash at September 30	884,380	805,154
Supplemental Cash Flow Information:
Income tax payments, net	54,161	46,122
Interest paid on deposits and borrowings	73,448	44,074
Loans transferred to foreclosed real estate	$ 558	$ 1,312